Imagine David and Samantha Cameron getting themselves written into an episode of the Archers during an election campaign. The governor of Monterrey and his wife appeared in a cameo role in the Mexican version of Ugly Betty, and that is the least of it.

In Mexico, political product placement is a highly organised and lucrative business. We report on claims that a secretive unit was set up inside Televisa, the world's largest Spanish-language broadcaster, to promote the favourite in Mexico's presidential campaign, Enrique Peña Nieto. Televisa, which denies the allegation, is not necessarily loyal to Peña Nieto's party, the Institutional Revolutionary party (PRI). It has dealt pragmatically in the past with rivals such as the conservative National Action party (PAN) and the leftwing party of the Democratic Revolution (PRD). Its loyalty appears to be to a power structure, not necessarily its temporary tenants. The story does, however, say much about the state of Mexico, and its lack of transparency and accountability 12 years into its democratic transition.

It has been a history of failure, not just of the outgoing president Felipe Calderón and his disastrous war on drugs, which if anything weakened the country's institutional capacity to deal with the drug barons, but also of Vicente Fox before him, who promised much, but did nothing about cleaning up the old political structure – instead this has been rebranded, using the telegenic face of Peña Nieto. PRI's makeover is clever. It has managed to confect a soft nostalgia around the memory of its hegemonic rule for most of the last century. Peña Nieto's message is that he knows how to get things done, that he will bring results.

Peña Nieto denies a special relationship with Televisa, which grew from a radio station in 1930 to an empire which, it is suggested, turned news into PRI propaganda and slanted entertainment shows. In the past they used telenovelas to preach to Mexicans to know their place and be happy with their lot. Today the unit known as "Team Handcock" is said to use social media and YouTube to launder their political message. One contract we publish actually states that the aim is to produce "videos that mock some of the errors and weak points of the National Action party".

Most of the above could just as accurately be written about an election in America or Britain. As we are daily being made only too aware, the relationship between our media and politicians is all too symbiotic. The point is not that this sort of thing happens everywhere, but that it subverts democracy wherever it occurs. It appears Mexican voters are being lulled into accepting political manipulation. With the honourable exception of the Yo Soy 132 student-led movement, the depressing thing is that these tactics generally work.

• This article was amended on 26 June 2012. The original did not follow the usual Spanish-speaking style for Enrique Peña Nieto's surname. This has been corrected